<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="../js/vue.js"></script>
</head>

<body>
    <div id="demo">
        <p>监视属性 - 今天天气: {{weather}}</p>
        <p><button @click="isHot=!isHot">变天</button></p>
    </div>
    <script>
        Vue.config.productionTip = false
        const vm = new Vue({
            el: '#demo',
            data: {
                isHot: true,
                weather:'炎热'
            }
        })

        // 与 watch配置项监视的差别，可以控制监视的时机
        vm.$watch('isHot', {
            handler(value) {
                this.weather =  value ? '炎热' : '凉爽'
            }
        })
    </script>
</body>

</html>